PARENT SESSION
Symposium 3: Linking ecological processes and environmental impacts across scales: Coastal ecology and energy development in the Caspian Sea and Gulf of Mexico
Organized by: S Tartowski, T Butler, and V Bashkin
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 517 C, Level 5, Palais des congrès de Montréal
A carbon budget for the North Caspian Sea.
Butler, Tom1, 2, Mitrofanov, Igor*,3, 1 Institute of Ecosystem Studies, Millbrook, NY, USA2 Cornell University, Ithaca, NY, USA3 Tethys, Montreal, Quebec, Canada
ABSTRACT- The North Caspian Sea, while representing only 25% of the surface area, and less than 1% of the entire Caspian Sea volume, is an extremely important region in regards to fisheries production. A carbon budget for the North Caspian Sea was developed to quantify the significance of various sources impacting the food web and the fisheries in this region. On an annual basis the Volga River supplies 4 to 9 Teragrams (Tg) of carbon to the system, while phytoplankton gross primary production is 14 to 22 Tg C, and bacteriaplankton production is about 2 Tg. Macrophyte production is less than 1 Tg and other forms of benthic production have not been quantified. Net exchange with the Middle Caspian is on the order of 2 Tg and most sediments are not rich in organic matter, indicating that most of the carbon entering the system is used within the North Caspian. Standing stocks of zooplankton are 0.017 to 0.024 Tg C while zoobenthic standing stocks (mainly mollusks and crustaceans), are 0.3 to 0.6 Tg C. Data on secondary productivity are limited. It appears that there is a healthy benthic community capable of supporting the many benthic feeding fish species found in the Caspian. Standing stocks of fish include commercially important Kilka (Clupeonella sp.) (0.019 Tg C), semi anadromous Vobla (Rutilus r.) and Bream (Abramis sp.) (0.020 Tg C). The three most important sturgeon species and there standing stock over the entire Caspian Sea are Beluga (Huso huso) (0.013 to 0.019 Tg C), Russian Sturgeon (A. guldenstadti) (0.006 to 0.011 Tg C) and the Stellate Sturgeon (A. stellatus) (0.004 to 0.007 Tg C). The biomass of sturgeon is down dramatically from levels in the 1970s and 1980s. However if the present fishery numbers are reasonably accurate there still are sturgeon out there. They are mostly small immature sturgeon. Hydrocarbons also enter the North Caspian. The main source of hydrocarbons are from river inputs (50% to 65%). The Volga River, which supplies about 80% of the total river input to the Caspian, is the major river source. Natural seepage of hydrocarbons also contribute a significant amount of hydrocarbons.
Key words: Sturgeon, Caspian